Low nitrogen content fuel with improved lubricity

ABSTRACT

A hydrocarbon fuel is described comprising a hydrocarbon fuel boiling in the gasoline boiling range containing not greater than about 5 wppm nitrogen. The lubricity of such fuel is improved by the addition thereto of ethanol.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to hydrocarbon fuels of low nitrogen contentsuitable for use in spark ignition internal combustion engines and tothe improvement in the lubricity for such low nitrogen fuel.

2. Summary of the Invention

Hydrocarbon fuel of low nitrogen content, useful in spark ignitioninternal combustion engines, containing fuel system assemblies requiringlubrication, such as submerged fuel pumps and/or fuel injectors hasunexpectedly been found to have its lubricity improved by the additionthereto of a minor quantity of ethanol.

DETAILED DESCRIPTION OF THE INVENTION

Hydrocarbon base fuel for use as a major component in a gasoline blend,useful in spark ignition internal combustion engines, boiling in thegasoline boiling range and having a low nitrogen content, in the rangeof about 5 wppm or less nitrogen (exclusive of nitrogen attributable toadditives) has been found to have poor lubricity qualities.

Some nitrogen compounds present in typical base gasoline serve asnatural lubricants to protect moving parts in fuel systems and enginesnot otherwise lubricated by the usual lubricating oil system. Reductionin the amount of such nitrogen compounds has been observed to beaccompanied by a reduction in the lubricity of the base gasoline.

It has surprisingly been found that the lubricity characteristics ofhydrocarbon base fuel useful as base gasoline and boiling in thegasoline boiling range and containing about 5 wppm nitrogen or less,preferably about 3 wppm nitrogen or less, more preferably about 2 wppmnitrogen or less, most preferably 0.5 wppm nitrogen or less asdetermined by method ASTM D 4629-96 are improved by blending suchhydrocarbon base fuel with ethanol. Preferably at least about 2 vol %ethanol, more preferably at least about 5 vol % ethanol, still morepreferably about 5 to 15 vol % ethanol based on the total volume of theblended fuel will be employed. The hydrocarbon fuel blend of the presentinvention will generally contain about 20 vol % or less ethanol, thuspreferably about 2-20 vol % ethanol, more preferably about 5-20 vol %ethanol, still more preferably about 5 to 15 vol % ethanol will be used.This effect on lubricity is unexpected and is contrary to the decreasein lubricity that results from the addition of ethanol to base gasolinecontaining a greater amount of nitrogen compounds boiling in thegasoline boiling range.

Hydrocarbon base fuel suitable as base gasoline in the present inventionpreferably also has low volatility and low sulfur to reduce emissionsand meet current and future regulatory targets.

By low sulfur is meant a sulfur content of the hydrocarbon base fuel ofabout 50 wppm or less, preferably about 10 wppm or less, more preferablyless than about 10 wppm, most preferably less than about 5 wppm asdetermined by test method ASTM D 5453-93.

The base fuel useful in the present invention is preferablycharacterized in that the nitrogen to sulfur weight ppm ratio is about0.01:1 to 1:1, preferably about 0.02:1 to 0.5:1, still more preferablyabout 0.03:1 to 0.5:1.

It is well known that ethanol increases volatility of the fuelcomposition when splash blended into gasoline due to deviation fromRaoult's Law (SAE Automotive Fuels Handbook, 1990, Chapter 11). In thepresent invention therefore, the Reid Vapor Pressure (RVP) of the basegasoline, prior to introduction of ethanol is preferably less than about9 psi, more preferably less than about 8 psi and most preferably lessthan about 7 psi. RVP as used herein and in the claims refers to the dryvapor pressure equivalent as determined by Institute of Petroleum methodIP 394.

The hydrocarbon base fuel is useful in spark ignition internalcombustion engines and boiling in the gasoline boiling range and can beeither leaded, additized with octane enhancing manganese compounds, orunleaded gasoline of any grade. Preferably, the fuel is unleadedgasoline of the aforesaid low nitrogen content level.

Base gasoline of the recited low nitrogen content can be produced bythose skilled in the gasoline refining art using any technique know tobe effective for the reduction of organic nitrogen present inhydrocarbon streams. Such techniques include methods such as adsorptionusing selective adsorbents, and catalytic hydrodenitrogenation.

The fuel composition comprising the base gasoline and ethanol typicallywill contain additives including detergents, deicing additives,anti-knock additives (other than lead compounds), anti-corrosionadditives, other anti-wear/lubricity improving additives,anti-oxidants,;anti-rust additives, etc. These can be added separatelyor in combination in one or more steps in any order to the fuelcomposition or any of its components. The term additive is meant toinclude any chemical added at any stage during the processing orblending of the fuel.

Suitable additives include, by way of example and not limitation, as,antioxidants, the aromatic diamines and alkyl phenols; as metaldeactivators, N,N'disalicylidene-1,2 propane diamine, to deactivate anycopper present in the gasoline; as corrosion inhibitors, polar moleculessuch as tall oil fatty acids/esters, esters or amine salts of alkenylsuccinic acids, alkyl orthophosphoric acids, alkyl phosphoric acids,aryl sulfonic acids; as biocides, various boron compounds, quaternaryammonium salts of salicylic acid, glycol ethers, etc.; anti staticagents; as drag reducing agents, various high molecular weight polymersthat shear readily and thus reduce drag; demulsifiers and dehazers; asanti-icing additives, various C₃+ alcohols or glycols; surfactantadditives such as amines or imidazoline salts of carboxylic or alkyenylsuccinic acids which also function as antiwear additives; as detergents,alkyl amine phosphates or fatty acid amides, alkenyl succinimides,polybutene amines and polyether amines; polymeric dispersants; othernitrogen compounds such as nitrogen containing octane enhancers, e.g.,aniline or its derivatives, or other organic amines. In addition,different carrier fluids or diluents can be used, including mineral oil,light aromatic solvents, esters such as polyol ester, or polymericmaterial such as polyolefins, polyethers or polyglycols. Other additivesthat can be present in gasoline include various anti knock additives,anti octane requirement increase additives, anti pre-ignition or misfireadditives, flame front accelerants, spark aid additive, anti valve seatrecession additives, upper cylinder head lubricants, anti wear additivesand anti sludge additives, all of which are types of materials wellknown in the gasoline formulation art.

The present fuel comprising gasoline having a nitrogen content of about5 wppm or less and containing at least 2 vol % ethanol is especiallyuseful in fueling internal combustion engines containing fuel systemassemblies requiring lubrication such as submerged fuel pump and fuelinjectors.

The ethanol used can be derived from any source, e.g., by directsynthesis, or by production form renewal resources, e.g., grain, etc.,by fermentation and distillation. It is preferred that the ethanol befuel grade ethanol as defined in, for example, ASTM D 4806-98.

The present invention is further illustrated by the following examplesand comparative examples which are not, however, to be construed aslimitations thereof.

EXAMPLES

The data in Table 1 demonstrate in Example 1 that ethanol improvesgasoline lubricity, as measured by friction coefficient, when nitrogenis less than about 5 wppm. The nitrogen content was measured accordingto ASTM D 4629-96 (employing Antek apparatus manufactured by AntekInstruments, Inc.). Sulfur content was measured using ASTM D 5453-93(employing Antek apparatus manufactured by Antek Instruments, Inc.). TheRVP was measured as the dry vapor pressure equivalent according toInstitute of Petroleum method IP 394 (employing a Setavap Analyzermanufactured by Stanhope-Seta). The data were generated using the HFRRfriction and wear test. The HFRR test procedure employed was amodification of European standard test CEC F-06-A-96 for diesel fuelsmodified for gasoline in that the test is run at 25° C. (as opposed to60° C. in the diesel test) and a cover is placed over the test cell toreduce evaporation of the gasoline sample under test. Data are alsoincluded, Comparative Examples 1 and 2, on two other gasoline sampleswith nitrogen content of 5.5 wppm and 18 wppm, respectively. Ethanoldoes not improve lubricity of these fuels. This demonstrates thatethanol improves lubricity in gasoline when nitrogen content is about 5wppm or less.

Example 2 was run using a different base gasoline than Example 1 andfurther demonstrates that the addition of ethanol to a base gasoline oflow nitrogen context improves the lubricity of such fuel. TABLE 1Gasoline Ethanol (Vol %) Friction Example 1 Sulfur = 9 wppm; Nitrogen =0.3 wppm; RVP = 7.4 psi 100 vol % 0 0.486  95 vol % 5 0.461  90 vol % 100.412 Comparative Sulfur = 51 wppm; Example 1 Nitrogen = 5.5 wppm; RVP =11.3 psi 100 vol % 0 0.368  95 vol % 5 0.379  90 vol % 10 0.43Comparative Sulfur = 180 wppm; Example 2 Nitrogen = 18 wppm; RVP = 10.6psi 100 vol % 0 0.347  95 vol % 5 0.342  90 vol % 10 0.355 Example 2Sulfur = <5 wppm; Nitrogen = 0.6 wppm; RVP = 11.1 psi 100 vol % 0 .50 95 vol % 5 .39  90 vol % 10 .37

1-18. (Cancelled).
 19. A method for improving the lubricity ofhydrocarbon fuel boiling in the gasoline boiling range and suitable foruse in a spark ignition internal combustion engine comprising a basefuel having a base fuel nitrogen content of about 5 wppm or lessnitrogen, exclusive of nitrogen attributable to additives, by adding tosaid fuel at least about 2 vol % ethanol.
 20. The method of claim 19wherein the fuel contains about 3 wppm or less of nitrogen.
 21. Themethod of claim 19 wherein the fuel contains about 2 wppm or less ofnitrogen.
 22. The method of claim 19 wherein the fuel contains about 0.5wppm or less of nitrogen.
 23. The method of claim 19, 20, 21 or 22wherein the base fuel is further characterized containing about 50 wppmor less of sulfur.
 24. The method of claim 19, 20, 21 or 22 wherein thebase fuel is further characterized containing about 10 wppm or less ofsulfur.
 25. The method of claim 19, 20, 21 or 22 wherein the base fuelis further characterized containing about 5 wppm or less of sulfur. 26.The method of claim 19, 20, 21 or 22 wherein at least about 5 vol %ethanol is added to the fuel.
 27. The method of claim 19, 20, 21 or 22wherein about 5 to 15 vol % ethanol is added to the fuel.
 28. The methodof claim 23 wherein at least about 5 vol % ethanol is added to the fuel.29. The method of claim 24 wherein at least about 5 vol % ethanol isadded to the fuel.
 30. The method of claim 25 wherein at least about 5vol % ethanol is added to the fuel.
 31. The method of claim 23 whereinabout 5 to 15 vol % ethanol is added to the fuel.
 32. The method ofclaim 24 wherein about 5 to 15 vol % ethanol is added to the fuel. 33.The method of claim 25 wherein about 5 to 15 vol % ethanol is added tothe fuel.
 34. The method of claim 23 wherein the nitrogen to sulfurweight ppm ratio of the fuel is about 0.01:1 to 1:1.
 35. The method ofclaim 17, 18, 19 or 20 wherein the fuel is further characterized ashaving a Reid Vapor Pressure of less than about 9 psi.
 36. (Cancelled)37. (Cancelled)
 38. A method for operating an internal combustion enginecontaining fuel system assemblies requiring lubrication includingsubmerged fuel pump, fuel injectors, or both by supplying to said enginea fuel comprising gasoline containing about 5 wppm or less nitrogen andat least about 2 vol % ethanol.
 39. (Cancelled)